Quick Answer
The answer is the DNS filter security profile. This is correct because the DNS filter is purpose-built to inspect and block outgoing DNS queries based on domain names, IP addresses, or category lists, making it the precise tool to block malware domains at the resolution stage. On the Fortinet NSE 4 Network Security Professional exam, this question tests your understanding of which security profile handles layer 7 DNS inspection versus other profiles like web filter or application control, which operate on HTTP or application traffic. A common trap is confusing the DNS filter with the web filter, but remember: the DNS filter blocks the query before the domain is even resolved, while the web filter blocks the subsequent HTTP request. For a memory tip, think “DNS first, web second”—the DNS filter stops the lookup, so the malware domain never gets an IP address to connect to.
This NSE4 practice question tests your understanding of security profiles. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A FortiGate administrator wants to block outgoing DNS requests to known malware domains. Which security profile should be used?
Application control
Why wrong: Application control identifies applications, but cannot filter DNS requests by domain.
Web filter
Why wrong: Web filter blocks HTTP/HTTPS URLs, not DNS queries.
IPS
Why wrong: IPS can detect DNS-related attacks but is not designed for domain filtering.
DNS filter
DNS filter can block DNS queries to malicious domains based on FortiGuard or custom categories.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
DNS filter
DNS Filter is the correct security profile because it is specifically designed to inspect and block DNS queries based on domain names, IP addresses, or categories. By configuring a DNS filter policy with a custom list of known malware domains, the FortiGate can intercept outgoing DNS requests and drop those matching the malicious entries, preventing the resolution of malware domains.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Application control
Why it's wrong here
Application control identifies applications, but cannot filter DNS requests by domain.
Web filter
IPS
DNS filter
Why this is correct
DNS filter can block DNS queries to malicious domains based on FortiGuard or custom categories.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse DNS Filter with Web Filter, assuming that blocking malicious domains is a web filtering function, but DNS Filter operates at the DNS protocol level and is the correct profile for blocking DNS requests to specific domains.
Detailed technical explanation
DNS Filter works by intercepting DNS requests at the application layer, matching the queried domain against configured filter lists (e.g., FortiGuard categories or custom domain/IP lists). When a match is found, the FortiGate can return a spoofed NXDOMAIN response or simply drop the packet, preventing the client from resolving the malware domain. This is more efficient than URL filtering because it blocks the resolution before any HTTP connection is attempted, reducing unnecessary traffic.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the NSE4 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Security Profiles — This question tests Security Profiles — Read the scenario before looking for a memorised answer..
The correct answer is: DNS filter — DNS Filter is the correct security profile because it is specifically designed to inspect and block DNS queries based on domain names, IP addresses, or categories. By configuring a DNS filter policy with a custom list of known malware domains, the FortiGate can intercept outgoing DNS requests and drop those matching the malicious entries, preventing the resolution of malware domains.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This NSE4 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE4 exam.
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